The present invention relates to an ocular characteristic measuring apparatus capable of measuring a light-intensity distribution characteristic of a target image formed on a fundus of an eye and of determining the ocular optical characteristic of the eye on the basis of the measured light-intensity distribution characteristic.
When measuring the ocular optical characteristic of an eye by a conventional ocular optical characteristic measuring apparatus, a target image is formed on the fundus of the eye, a reflected target image is formed on a photoelectric device by reflected light, light-intensity distribution on the reflected target image is measured, and the point spread on the eyeball indicating the optical characteristic of the eye is determined on the basis of the measured data.
The light-intensity distribution on the target image measured by this conventional ocular optical characteristic measuring apparatus indicates the point spread on the ocular optical system of the eye. The reflected light from the image travels through the ocular optical system again and fall on the photoelectric device. Therefore, it has been thought that the light-intensity distribution in the target image formed on the photoelectric device can be expressed by the superposition integration of the point spread.
When measuring the ocular optical characteristic of the eye by the conventional ocular optical characteristic measuring apparatus, target light projected on the fundus reach not only the surface of the fundus but also a part of the fundus slightly below the surface of the fundus and the light is scattered and reflected to cause the so-called xe2x80x9cblurred reflectionxe2x80x9d.
The light reflected in a blurred reflection mode by the fundus affect the light-intensity distribution in the target image formed on the photoelectric device. Consequently, the light-intensity distribution in the target image formed on the photoelectric device does not represent accurately the superposition integration of the point spread in the ocular optical system and hence the point spread in the ocular optical system cannot be calculated exactly on the basis of only the measured light-intensity distribution.
Therefore, the development of an ocular optical characteristic measuring apparatus capable of preventing scatter-reflected light reflected by the fundus in a blur reflection mode from falling on a photoelectric device, of forming a target image on the photoelectric device only by light regularly reflected by the fundus surface and preventing the effect of unmeasurable blur reflection particular to the eye on the measurement was strongly desired.
According to the present invention, a projection optical system projects light emitted by a light source on the fundus of an eye to form a target image on the fundus. A light receiving optical system guides reflected light reflected from the fundus to a photoelectric device to form a target image on the photoelectric device and measures a light-intensity distribution in the target image formed on the photoelectric device according to a signal from the photoelectric device to determine the ocular optical characteristic of the eye. Substantially all scatter-reflected light is removed from the reflected light reflected by the fundus of the eye.